Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Apr:195:110793.
doi: 10.1016/j.envres.2021.110793. Epub 2021 Jan 27.

Large-scale IgM and IgG SARS-CoV-2 serological screening among healthcare workers with a low infection prevalence based on nasopharyngeal swab tests in an Italian university hospital: Perspectives for public health

Luigi Vimercati  1 , Pasquale Stefanizzi  2 , Luigi De Maria  3 , Antonio Caputi  3 , Domenica Cavone  3 , Marco Quarato  3 , Loreto Gesualdo  4 , Pier Luigi Lopalco  5 , Giovanni Migliore  6 , Stefania Sponselli  3 , Giusi Graziano  2 , Angela Maria Vittoria Larocca  2 , Silvio Tafuri  2
Affiliations

Large-scale IgM and IgG SARS-CoV-2 serological screening among healthcare workers with a low infection prevalence based on nasopharyngeal swab tests in an Italian university hospital: Perspectives for public health

Luigi Vimercati et al. Environ Res. 2021 Apr.

Abstract

Background: Healthcare workers (HCWs) are highly exposed to SARS-CoV-2 infection given their specific tasks. The IgG-IgM serological assay has demonstrated good accuracy in early detection in symptomatic patients, but its role in the diagnosis of asymptomatic patients is uncertain. The aim of our study was to assess IgM and IgG prevalence in sera in a large cohort of HCWs previously subjected to Nasopharyngeal swab test (NST) after accurate risk assessment due to positive COVID-19 patient exposure during an observation period of 90 days.

Methods: 2407 asymptomatic HCWs that had close contact with COVID-19 patients in the period between April 8th and June 7th were screened with NST based on the RT-PCR method. In parallel, they underwent large-scale chemiluminescence immunoassays involving IgM-IgG serological screening to determine actual viral spread in the same cohort.

Results: During the 90-day observation period, 18 workers (0.75%) resulted positive for SARS-CoV-2 infection at the NST, whereas the positivity rates for IgM and IgG were 11.51% and 2.37%, respectively (277 workers). Despite high specificity, serological tests were inadequate for detecting SARS-CoV-2 infection in patients with previous positive NST results (IgM and IgG sensitivities of 27.78% and 50.00%, respectively).

Conclusions: These findings indicate a widespread low viral load of SARS-CoV-2 among hospital workers. However, serological screening showed very low sensitivity with respect to NST in identifying infected workers, and negative IgG and IgM results should not exclude the diagnosis of COVID-19. IgG-IgM chemiluminescence immunoassays could increase the diagnosis of COVID-19 only in association with NST, and this association is considered helpful for decision-making regarding returning to work.

Keywords: COVID-19; Healthcare workers; Serological screening.

PubMed Disclaimer

Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Prevalence of positive IgG results.
Fig. 2
Fig. 2
Geometric mean values of IgG.
See this image and copyright information in PMC

References

    1. Alessio L., Porru S., Aparo U.L., Bassetti D., Beltrame A., Buzzi F., Cipolloni L., Germano T., Lombardi R., Longo F., et al. Linee Guida per la Sorveglianza Sanitaria dei Lavoratori della Sanità esposti a rischio biologico. Soc. Ital. Med. Lavoro ed Igiene Ind.: PIME: Pavia, Italy. 2005;ume 17
    1. Batra R., Olivieri L.G., Rubin D., Vallari A., Pearce S., Olivo A., Prostko J., Nebbia G., Douthwaite S., Rodgers M., Cloherty G. A comparative evaluation between the Abbott Panbio™ COVID-19 IgG/IgM rapid test device and Abbott Architect™ SARS CoV-2 IgG assay. J. Clin. Virol. 2020 Sep 16;132:104645. doi: 10.1016/j.jcv.2020.104645. Epub ahead of print. PMID: 32961429; PMCID: PMC7493757. - DOI - PMC - PubMed
    1. Bhattacharya S., Basu P., Poddar S. Changing epidemiology of SARS-CoV in the context of COVID-19 pandemic. J Prev Med Hyg. 2020;61(2):E130–E136. doi: 10.15167/2421-4248/jpmh2020.61.2.1541. Published 2020 Jul 4. - DOI - PMC - PubMed
    1. Böger B., Fachi M.M., Vilhena R.O., Cobre A.F., Tonin F.S., Pontarolo R. Systematic review with meta-analysis of the accuracy of diagnostic tests for COVID-19 [published online ahead of print, 2020 Jul 10] Am. J. Infect. Contr. 2020;S0196–6553(20):30693. doi: 10.1016/j.ajic.2020.07.011. 3. - DOI - PMC - PubMed
    1. Center for Disease Control https://www.cdc.gov/coronavirus/2019-ncov/hcp/testing-overview.html